Battery maintainer install directly to 12V battery

Just need to point out that, even though the more recent question was posted in a thread about battery maintainers, that poster doesn't actually need one. They live in southern California and they don't own a Prime/PHV. Giving them advice on how to permanently install a battery maintainer doesn't really help them. As long as they don't sit in the driveway listening to music in ACC or POWER ON mode, they aren't going to have any problems.

 

LoL; Always route the power cord pass or over your driver's side mirror, flip the sun visor down, or a large sign on your steering wheel. That's how I make sure I don't drag a plug.
If you want to get really fancy; you can use a relay to disable the brake switch. That way you can't start the car when your plugged in. The PHEV won't start with the charge door open, so you can wire-in there, without disturbing the brake switch wiring.

There are many ways to prevent you from dragging a plug. You just need to figure one out and stick with it. Over time it'll become routine, especially as we get older and forgetful.

Hope this helps....

 

Don’t attach jumper cables or a battery maintainer directly to your battery. she the points under your hood. And it’s best to never use jumper cables and use a jump pack (battery) instead.

 

I have connected a pigtail quick connector directly to the 12V battery in the back, and did charge the 12V battery fully two days ago with a CTEK charger. Should I have not done this? Why? You have me worried.....

I do also plan to connect a pigtail quick connector under the hood for my CTEK charger based on the pics and instructions earlier in this thread.

 

I haven't used a jump pack in over a year, but I still carry one. My precautions seem to have prevented having a dead battery so far. I have a bypass switch on my auxiliary battery, but if I ever need it, I won't be able to access the rear hatch to use it. Maybe what I need is a remote switch from the front seat. I know there is a manual pull handle somewhere, but I'm a long way past being able to crawl back there to access it.

I have an idea for another mod; I am able to order a remote switch, capable of handling 40 amps which I can use to bypass the battery isolator. They are less than $3 on Aliexpress, so I ordered two different models. The exact same thing on Amazon sells for over $30. They have 2 channels, A and B, so perhaps I can wire one to bypass the aux battery, and the other one for the rear hatch release. This way, when the battery is dead, I can activate a boost from the aux battery. I have a 30 amp breaker already in the bypass switch circuit. I can either replace the toggle switch or run this relay in parallel with it. I think I'll leave the toggle switch as a backup.

 

Nothing broke, so nothing to worry about.

My BMW has similar rigmarole attached to the battery. Its purpose is to detect phantom power draws and to shut off systems when the car is powered off to ensure that the battery doesn’t die. It’s because cars are full of systems that keep running when the car’s off, like remote start, keyless entry, etc.

So it’s best not to use another car to jumpstart, because of voltage spikes, and it’s best to attach the battery tender up front from now on.

 

It is OK to jump-start from another car.

You can connect the battery maintainer wherever you want. It makes no difference.

 

What is your basis for that determination?

 

A battery maintainer can be connected to any battery, any time. It simply monitors battery voltage periodically, and if the battery can take a charge, it delivers one. This differs from a trickle charger, which applies a small current to the battery constantly.

I have ordered a voltage/current logger to see when the battery is charging while sitting idle. This can give a clue about parasitic drain.

 

Sorry, need to chime in here.
Stay away from those charger/maintainer that claim to desulfate batteries. It does so by sending high energy pulses, that may damage your electrical system. Power supply capacitor are suppose to filter that out, but on an old tired dried out one - good luck.....
Some of those units instructs you to remove or disconnect the battery from the car; but who reads instructions.

Just something to think about, sometimes all you need is some good clean DC current.....

 

On the Noco Genius, it is safe to charge the battery in the car in the normal flooded-cell or AGM modes. However, yes, if you decide to use the repair mode, you need to disconnect the battery from the car as instructed in the manual since the voltages could be too high and damaging.

 

My Gen 3 manual says this:



Which I've never done.

 

But are you using an old school battery charger or one of those high frequency pulse battery desulfator / refurbisher?
As stated earlier, you can probably get away with it - until you don't and fry something. The simplest thing to do is, turn-off and don't use that option or disconnect one of your cables. It's your car and you can do whatever you want to it.
I know a lot of people, professionals included, who jump start a car by connecting battery terminal to battery terminal - NOT to engine block or other ground point. They can get away with that, but what happens in that 1 in 1000 chance that the battery explodes in their face? Not worth it to me, I prefer to do it the correct way - but that's just me....

PS, the Toyota manual states that so they don't get sued in that 1 in 1000 chance.

 

You can turn off the battery maintainer before you remove the wires, which eliminates any spark hazard, the latter of which is the reason for the note in the owner’s manual.